Content addressable memory cells and arrays are well known in the art. U.S. Pat. No. 5,949,696 discloses a differential volatile content addressable memory cell and an array made thereby.
Non-volatile content addressable memory cells and arrays are also well known in the art. U.S. Pat. No. 5,930,161 discloses a non-volatile content addressable memory cell and array using ferroelectric capacitors as storage elements.
Non-volatile floating gate storage elements are also well known in the art. These can be of the stacked gate type or the split gate type as exemplified by U.S. Pat. No. 5,029,130.
A differential non-volatile content addressable memory cell comprising a pair of nonvolatile storage elements, and an array is also shown in U.S. Pat. No. 6,639,818.
However, heretofore, all non-volatile differential content addressable memory cells and array have used a word line through the cells that are arranged in the same row to activate those cells.
Phase changing resistors, such as chalcogenide storage elements are also well known in the art.
It is therefore, an object of the present invention to provide a non-volatile differential content addressable memory without the use of word lines.